An exercise bike is better than nothing.

A spin bike is better than an exercise bike ... as I mentioned earlier, if you can get into spin classes a couple days a week, that'll help get you in shape for a tour. And personally, I find that an hour on a spin bike in a class with other people and an instructor and music, etc. makes the time go by quite quickly.

A trainer or rollers are possibly somewhat better than a spin bike. Do "commercial intervals" ... where you pick a 30-60 minute show you like, ride easy through the show, and ride hard during the commercials ... once or twice a week.

But best of all ... ride outside. Even in bad weather ... maybe especially in bad weather. During a 9 week tour, you'll have a decent chance of encountering bad weather somewhere along the way ... wouldn't hurt to encounter it while preparing so you can make decisions about clothing, mud guards, etc. Ride on a variety of terrain. Ride with bags on your bicycle ... at least some of the ones you'll be using. And ride ever-increasing distances.

The thing is ... riding ever-increasing distances on the bicycle you intend to use for the tour will help you identify fit issues and saddle issues and whatever other issues there may be ... and you'll have time to fix them.